Given someone is really a Christian, there would be zero influence of demons in their life.
Did someone do something wrong, in sin, where they need to be 100% repentant, and confess their sins?
Sin isn't just actions; it is attitudes and desires like pride, impatience, impulsiveness, lust, and others. The demons at Satan's urging attack Christians at their weakest points. We need to ask for God's cleansing power through Jesus' resurrection every day and to pray for godly qualities like the fruit of the Spirit to replace the selfish ones. It's a lifelong battle.
Col 3:1 If ye then be risen with Christ, seek those things which are above, where Christ sitteth on the right hand of God.
Col 3:2 Set your affection on things above, not on things on the earth.
Col 3:3 For ye are dead, and your life is hid with Christ in God.
Col 3:4 When Christ, who is our life, shall appear, then shall ye also appear with him in glory.
Col 3:5 Mortify therefore your members which are upon the earth; fornication, uncleanness, inordinate affection, evil concupiscence, and covetousness, which is idolatry:
Col 3:6 For which things' sake the wrath of God cometh on the children of disobedience:
Col 3:7 In the which ye also walked some time, when ye lived in them.
Col 3:12 Put on therefore, as the elect of God, holy and beloved, bowels of mercies, kindness, humbleness of mind, meekness, longsuffering;
Col 3:13 Forbearing one another, and forgiving one another, if any man have a quarrel against any: even as Christ forgave you, so also do ye.
Gal 5:19 Now the works of the flesh are manifest, which are these; Adultery, fornication, uncleanness, lasciviousness,
Gal 5:20 Idolatry, witchcraft, hatred, variance, emulations, wrath, strife, seditions, heresies,
Gal 5:21 Envyings, murders, drunkenness, revellings, and such like: of the which I tell you before, as I have also told you in time past, that they which do such things shall not inherit the kingdom of God.
Gal 5:22 But the fruit of the Spirit is love, joy, peace, longsuffering, gentleness, goodness, faith,
Gal 5:23 Meekness, temperance: against such there is no law.